The preparation method of methyl anthranilate comprises the following steps:
(1) 25% ammoniacal liquor of 937kg10 ℃ is put into amidation reactor, 1000kg phthalic anhydride is dropped in the amidation reactor, and ammoniacal liquor and phthalic anhydride react in the environment below 30 ℃ to generate o-formamide benzoic acid ammonium, react Time 2.5h. The 25% ammoniacal liquor that actually participates in the amidation reaction is 892.3kg, and 937kg of 25% ammoniacal liquor is added for the amidation reaction to be more complete.
(2) After the amidation reaction, put into the sodium hydroxide solution of 879kg30% in the amidation reactor, o-formamide benzoic acid ammonium and sodium hydroxide generation displacement reaction generate sodium o-formamide benzoate, then the amidation reactor The temperature inside rises to 50°C, and the ammonia molecules in the mixed solution are evaporated, and the evaporated ammonia gas is led by the induced draft fan to the two-stage series water absorption tower for water absorption to obtain ammonia water, and the ammonia water is sent to the ammonia water storage tank, and then to the ammonia water storage tank Add liquid ammonia inside to make 25% ammonia water for reuse.
(3) put the solution in the amidation reactor into the esterification reactor, put into the methanol solution of 1561kg75% and the sodium hypochlorite solution of 3451kg14% in the reactor, keep the temperature in the esterification reactor to be 10 DEG C, react A paste-like methyl anthranilate was generated, and the reaction time was 3 hours. After the reaction, the temperature in the esterification reactor was raised to 50°C. Add 1000kg hot water in the esterification reactor after the dissolving of pasty methyl anthranilate.
(4) Send the solution in the esterification reaction kettle into the methyl ester settling tank and let it stand for separation. The solution in the upper layer is pumped into the methanol recovery process, and the solution in the lower layer is filtered by a jet vacuum pump to obtain the filtrate. Stand still and separate, pump the solution in the upper layer into the methanol recovery process, put the filtrate in the lower layer into the distillation pot, and carry out distillation in an environment with a pressure of 2.00Kpa and a temperature of 135.5°C to obtain a finished product.
The solution sent to the methanol recovery process is pumped into the methanol rectification tower. Using the different boiling points of the components in the solution, the methanol in the solution is evaporated first, and the methanol vapor is condensed to obtain a methanol solution. The remaining solution is cooled and crystallized. Send it to the centrifuge, and after centrifugation, it can be sold as industrial salt.